Industrial drilling and cutting presents an ever-present problem concerning the removal of particulate matter formed by the drilling or cutting process. In manual and automated drilling and cutting processes, the particulate usually serves no useful purpose. In many situations, the particulate creates an undesirable environment around the drilling or cutting site and may interfere with subsequent drilling in a repetitive drilling or cutting situation. When the drilling relates to industrial processing of precious metals, e.g. gold or platinum, it is usually desirable to collect and reprocess the collected particulate. In other instances, where the waste particulate has little to no value it is desirable to remove and dispose of the created particulate.
An example of particulate matter that is desirable to remove and dispose of ocurrs in the pharmaceutical industry. Much effort has been devoted to the continued development and improvement of controlled release pharmaceutical formulations. The use of controlled release formulations can facilitate patient compliance with a particular dosing regimen. One known method employed for producing controlled release tablets is to provide a coating surrounding a tablet core containing an active ingredient, and to incorporate in that coating a hole or plurality of holes to allow fluid to penetrate through the membrane. The active ingredient in the tablet core is dissolved or suspended by the fluid penetrating the membrane and then exits the tablet through the hole in order to provide bioavailability of the active ingredient. It is important for consistent bioavailability that the hole has a precise size and shape. Accordingly, the procedure for hole formation must be precisely controlled such that each tablet is formed with a hole or holes that are consistently reproducible in diameter, depth and location on the tablet in order that the tablets exhibit substantially similar characteristics regarding drug release.
The particulate matter formed during the drilling of these holes can interfere with the precise formation of the hole. Once a tablet is drilled, the particulate matter that is created by the drilling process can become airborne in the vicinity of the drilling. This poses two problems. First, the particulate matter may be deposited on or near the laser lens, which may interfere with subsequent drilling of tablets. If the laser firing is not consistent or the precision is not reproducible for each tablet, the uniformity in size, shape, and depth of the holes that are formed can be negatively affected. Current Good Manufacturing Practice demands uniformity of drug delivery. If the holes cannot be drilled in a consistent and reproducible manner, it will alter the uniformity of delivery.
Another problem that can arise in the tablet drilling process is that the resulting particulate matter can settle back onto a tablet surface or resettle into the hole, which has been drilled into a tablet. Resettling of particulate matter into a hole that has been drilled may alter the release characteristics of the tablet. This also can result in lack of uniform release among tablets that are otherwise identical. Therefore what is needed is a means for removing the particulate matter from the region of drilling, and transporting or collecting of the particulate matter away from a tablet after it has been drilled.
Machines which are suitable for the laser drilling of tablets are described in U.S. Pat. Nos. 5,294,770, 5,399,828, and 5,783,793, which are incorporated herein by reference. Of the machines commercially available, great effort has been taken to ensure the precision, accuracy and reproducibility of the laser mechanism. However, the processing factor of particulate removal from the drilling site has been neglected in currently available laser drilling machines.